public class TestDemo {

	public static void main(String[] args) {
		
		Gen<Integer> g1 = new Impl1();
		System.out.println(g1.add(10, 20));
		
		Gen<Integer> g2 = new Impl2<Integer>();
		System.out.println(g2.add(10, 20));
		
		Gen<Double> g3 = new Impl2<Double>();
		System.out.println(g3.add(10.0, 20.0));
		
		Gen<String> g4 = new Impl2<String>();
		System.out.println(g4.add("abc", "123"));

	}

}